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Chapter 30

Electromagnetic Induction

Induzione
Induzione
An emf is induced when the magnetic field in a coil is changed by pushing a bar magnet into or out of the coil. emfs of opposite signs are produced by ...
Legge di Faraday
Legge di Faraday
Faraday's law state that the induced emf is the negative change in the magnetic flux per unit of time. Any change in the magnetic field or change in ...
Legge di Lenz
Legge di Lenz
The direction in which the induced emf drives the current around a wire loop can be found through the negative sign. However, it is usually easier to ...
Campi elettromagnetici motori
Campi elettromagnetici motori
Magnetic flux depends on three factors: the strength of the magnetic field, the area through which the field lines pass, and the field's orientation ...
Dinamo a disco di Faraday
Dinamo a disco di Faraday
A Faraday disk dynamo is a DC generator, producing an emf that is constant in time. It consists of a conducting disk that rotates with a constant angular ...
Campi elettrici indotti
Campi elettrici indotti
The fact that emfs are induced in circuits implies that work is being done on the conduction electrons in the wires. What can possibly be the source of ...
Campi Elettrici Indotti: Applicazioni
Campi Elettrici Indotti: Applicazioni
An important distinction exists between the electric field induced by a changing magnetic field and the electrostatic field produced by a fixed charge ...
Correnti parassite
Correnti parassite
Since eddy currents occur only in conductors, magnets can separate metals from other materials. For example, in a recycling center, trash is dumped in ...
Corrente di spostamento
Corrente di spostamento
Ampère's law, in its usual form, does not work in places where the current changes with time and is not steady. Thus, Maxwell suggested including ...
Significato della corrente di spostamento
Significato della corrente di spostamento
A displacement current is analogous to a real current in Ampère's law, participating in Ampère's law the same way as the usual ...
Campi elettromagnetici
Campi elettromagnetici
Electric fields generated by static charges, often referred to as electrostatic fields, are characteristically different from electric fields created by ...
Equazione dell'elettromagnetismo di Maxwell
Equazione dell'elettromagnetismo di Maxwell
James Clerk Maxwell (1831–1879) was one of the major contributors to physics in the nineteenth century. Although he died young, he made major ...
Simmetria nelle equazioni di Maxwell
Simmetria nelle equazioni di Maxwell
Once the fields have been calculated using Maxwell's four equations, the Lorentz force equation gives the force that the fields exert on a charged ...
Legge di Ampere-Maxwell: Risoluzione dei problemi
Legge di Ampere-Maxwell: Risoluzione dei problemi
A parallel-plate capacitor with capacitance C, whose plates have area A and separation distance d, is connected to a resistor R and a battery of voltage ...
Forma differenziale delle equazioni di Maxwell
Forma differenziale delle equazioni di Maxwell
James Clerk Maxwell (1831–1879) was one of the significant contributors to physics in the nineteenth century. He is probably best known for having ...
Generatore elettrico: Alternatore
Generatore elettrico: Alternatore
Electric generators induce an emf by rotating a coil in a magnetic field. A simple alternator is an AC generator that creates electrical energy that ...
Generatore CC
Generatore CC
An alternator converts mechanical energy into electrical energy that varies sinusoidally, resulting in AC current. Meanwhile, a DC generator converts ...
Campi elettromagnetici posteriori
Campi elettromagnetici posteriori
Generators convert mechanical energy into electrical energy, whereas motors convert electrical energy into mechanical energy. A motor works by sending a ...
Smorzamento magnetico
Smorzamento magnetico
Eddy currents can produce significant drag on motion, called magnetic damping. For instance, when a metallic pendulum bob swings between the poles of a ...
Superconduttore
Superconduttore
A substance that reaches superconductivity, a state in which magnetic fields cannot penetrate, and there is no electrical resistance, is referred to as a ...
Tipi di superconduttori
Tipi di superconduttori
A superconductor is a substance that offers zero resistance to the electric current when it drops below a critical temperature. Zero resistance is not the ...
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